Fan wheel structure for a blower fan

ABSTRACT

A fan wheel structure comprises an annular wall, a central shaft extending along a central axis of the annular wall, an annular bottom plate extending outward from a bottom of the annular wall, and plural blades provided on the bottom plate. A joint area between the annular wall and the annular bottom plate is an annular arcuate wall to avoid interference with the air driven by the fan wheel, thereby providing a smoother airflow.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a fan wheel structure for ablower fan. In particular, the present invention relates to a fan wheelstructure for a blower fan that drives air to flow in an improved,smoother manner.

[0003] 2. Description of the Related Art

[0004]FIG. 1 of the drawings illustrates a conventional blower fancomprising a casing 90 having an axle tube 91 around which a stator 92is mounted. A bearing 93 is mounted in the axle tube 91 for rotatablyholding a central shaft 95 of a fan wheel 94. The fan wheel 94 comprisesan annular wall 98 and an annular plate 96 extending radially outwardfrom a bottom edge of the annular wall 98. Plural blades 97 are mountedupright on an annular outer edge of the annular plate 96 and spaced fromthe annular wall 98 by an appropriate gap. When the fan wheel 94 isdriven to turn, air is sucked into the blower fan and exits via anoutlet by the blades 87. Such a conventional blower fan creates asuction force for driving the air by means of a turbulent flow passingthrough a swirl passage in the casing 90. Therefore, the blowing effectlargely depends on the smoothness of the flow. However, the joint areabetween the annular wall 98 and the annular plate 96 is at a right anglesuch that the sucked air would accumulate in the joint area and thusform turbulence.

[0005] Taiwan Utility Model Publication No. 388203, issued to Applicanton Apr. 21, 2000 and entitled AN WHEEL STRUCTURE as illustrated in FIG.2 of the accompanying drawings of the present application, discloses afan wheel 80 comprising plural axial flow blades 82 and plural blowerblades 83 on an outer periphery of an annular wall 81 thereof. When theannular wall 82 turns, the axial flow blades 82 drives air along anaxial direction while the blower blades 83 drives air along a directionorthogonal to the axial direction.

SUMMARY OF THE INVENTION

[0006] It is the primary object of the present invention to provide afan wheel structure for a blower fan that drives air to flow in animproved, smoother manner, thereby providing an improved blowing effect.

[0007] The fan wheel structure in accordance with the present inventioncomprises an annular wall, a central shaft extending along a centralaxis of the annular wall, an annular bottom plate extending outward froma bottom of the annular wall, and plural blades provided on the bottomplate. A joint area between the annular wall and the annular bottomplate is an annular arcuate wall to avoid interference with the airdriven by the fan wheel, thereby providing a smoother airflow.

[0008] Other objects, specific advantages, and novel features of theinvention will become more apparent from the following detaileddescription and preferable embodiments when taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a sectional view of a conventional blower fan.

[0010]FIG. 2 is an exploded perspective view of another conventionalblower fan.

[0011]FIG. 3 is an exploded perspective view of a blower fan inaccordance with the present invention.

[0012]FIG. 4 is a sectional view of the blower fan in accordance withthe present invention.

[0013]FIG. 5 is a sectional view similar to FIG. 4, illustrating amodified embodiment of the blower fan in accordance with the presentinvention.

[0014]FIG. 6 is an enlarged sectional view illustrating an annular walland an annular bottom plate of the blower fan in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Preferred embodiments in accordance with the present inventionwill now be described with reference to the accompanying drawings.

[0016] Referring to FIG. 3, a blower fan in accordance with the presentinvention generally comprises a casing 11 defining a swirl passage 11and a stator 12 mounted in the casing 11 for rotatably mounting a fanwheel 2. A lid 13 is provided to enclose the casing 1 and has an inlet14 through which air is sucked into the swirl passage 11 and then exitsthe casing 11 via an outlet 15 located in a side of the casing 11.

[0017] The fan wheel 2 comprises an annular wall 22 and a central shaft21 extending along a central axis of the annular wall 22. The centralshaft 21 is rotatably mounted in the stator 12. A permanent ring magnet23 is mounted to an inner periphery of the annular wall 22. An annularbottom plate 24 extends outward from a bottom of the annular wall 22 andplural upright blades 25 are mounted on the annular bottom plate 24.

[0018] Referring to FIGS. 3 and 4, the main feature of the fan wheel inaccordance with the present invention resides in that the annular wall24 is not orthogonal to the annular bottom plate 24. A joint areabetween the annular wall 24 and the annular bottom plate 24 is anannular arcuate wall 26 that may directly extend from the annular wall22 toward the annular bottom plate 24, thereby providing a smooth airpassage between the inlet 14 and the outlet 15 of the fan.

[0019] Referring to FIGS. 5 and 6, the annular bottom plate 24 extendsoutward and downward such that the angle between the annular bottomplate 24 and the annular wall 22 is obtuse, which makes the airflowsmoother.

[0020] According to the above description, it is appreciated that thefan wheel structure in accordance with the present invention provides asmoother airflow passage for the driven air by means of providing anannular arcuate wall 26 between the annular wall 22 and the annularbottom plate 24. The airflow is even smoother when the angle between theannular bottom plate 24 and the annular wall 22 is obtuse by means ofoutward and downward extension of the annular bottom plate 24 away fromthe annular wall 22.

[0021] Although the invention has been explained in relation to itspreferred embodiment as mentioned above, it is to be understood thatmany other possible modifications and variations can be made withoutdeparting from the scope of the invention. It is, therefore,contemplated that the appended claims will cover such modifications andvariations that fall within the true scope of the invention.

What is claimed is:
 1. A fan wheel structure for a blower fan, the fanwheel structure comprising an annular wall having a bottom, a centralshaft extending along a central axis of the annular wall, an annularbottom plate extending outward from the bottom of the annular wall, andplural blades mounted on the annular bottom plate, a joint area betweenthe annular bottom plate and the annular wall being an annular arcuatewall.
 2. The fan wheel structure for a blower fan as claimed in claim 1,wherein the annular bottom plate and the annular wall have an obtuseangle therebetween.